Arizona Sen. John McCain’s presidential aspirations stand to suffer a stunning setback if California Republicans carry out a plan to move part of their nomination process up from June to Feb. 5 next year.

“If the California Republican Party approves this idea, it may benefit candidates other than Senator John McCain,” Orange County state Assemblyman Chuck DeVore told The Washington Times.

The proposal backed by Mr. DeVore, an influential conservative activist, calls for the 1,600 members of the state Republican Central Committee to select at least 53 of their 165 delegates to the 2008 Republican National Convention at the California party’s regularly scheduled February convention in Sacramento.

An alternative plan being negotiated by Republican Gov. Arnold Schwarzenegger and the Democrat-controlled state Assembly would move the 2008 presidential primary election up from its traditional June date — where it has in recent years had no effect on the selection of the party’s presidential nominee — to Feb. 5.

Florida is also expected to move its Republican primary to Feb. 5. Florida Gov. Charlie Crist, a Republican, is expected to put his statewide campaign machinery at the disposal of Mr. McCain for the presidential primary in that delegate-rich state.

Several other states are also planning to move up their primaries to early 2008, which political analysts predict would mean that nominees of both parties will be known after the votes are counted on Feb. 5.

California officials say moving the presidential primaries up to February — while leaving the primary elections for other offices as scheduled for June — will cost state taxpayers an extra $90 million.

“DeVore’s plan would save taxpayers $90 million and give the Republican Party here a big say in who our presidential nominee is and do it without an unneeded primary election in February,” said Republican state Assemblyman Doug LaMalfa.

The real reason the Legislature wants to change the primary date, Mr. DeVore said, is to get on the ballot an extension of term limits, adding six more years for Assembly members and four more years for state Senate members.

“This election has two purposes: To impact the presidential nomination process and to place a term-limit extension initiative on the ballot in time for some lawmakers to run for re-election during the regularly scheduled June 2008 primary,” Mr. DeVore said.

Mr. LaMalfa said he is “inclined to help” get the DeVore plan taken up by the state party convention meeting less than two weeks from now.

Mr. McCain is widely viewed as the 2008 Republican presidential nomination front-runner nationally. In California, he is expected to benefit from the tacit support and perhaps formal endorsement of Mr. Schwarzenegger. But many Republican leaders in the state — who would vote in the February convention under Mr. DeVore’s plan — oppose Mr. McCain.

“The activists on the state central committee here have still not forgiven him for the McCain-Feingold assault on the First Amendment nor do they appear comfortable with his incoherent philosophical agenda,” Mr. DeVore said. “Senator McCain seems to be more a product of the New York Times than of the party of Ronald Reagan.”

California Republicans note that several top Schwarzenegger operatives — including Steve Schmidt, a former spokesman for the Bush-Cheney 2004 campaign and most recently campaign manager of Mr. Schwarzenegger’s successful re-election bid — have joined Mr. McCain’s operation as senior advisers.